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Biological Chemistry

Editor-in-Chief: Brüne, Bernhard

Editorial Board Member: Buchner, Johannes / Ludwig, Stephan / Sies, Helmut / Turk, Boris / Wittinghofer, Alfred

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Cooperative and independent activities of Sgt2 and Get5 in the targeting of tail-anchored proteins

Christian Kohl1 / Peter Tessarz1, a / Karina von der Malsburg1, b / Regina Zahn1 / Bernd Bukau1 / 1

1Zentrum für Molekulare Biologie der Universität Heidelberg (ZMBH), DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany

aPresent address: The Gurdon Institute, Tennis Court Road, Cambridge CB2 1QN, UK.

bPresent address: Institut für Biochemie und Molekularbiologie, Universität Freiburg, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany.

Corresponding author

Citation Information: Biological Chemistry. Volume 392, Issue 7, Pages 601–608, ISSN (Online) 1437-4315, ISSN (Print) 1431-6730, DOI: 10.1515/bc.2011.066, June 2011

Publication History

Published Online:


TPR proteins modulate the activity of molecular chaperones. Here, we describe the S. cerevisiae TPR protein Sgt2 as interaction partner of Ssa1 and Hsp104 and as a component of the GET pathway by interacting with Get5. The GET pathway mediates the sorting of tail-anchored (TA) proteins, harboring a C-terminal trans-membrane segment, to the ER membrane. S. cerevisiae sgt2Δ cells show partial defects in TA protein sorting. Sgt2 activity in vivo relies on its N- and C-terminal domains, whereas the central TPR domain and thus chaperone interactions are dispensable. We show that TA protein sorting defects are more severe in sgt2Δ get5Δ mutants compared to single knockouts. Furthermore, overproduction of Sgt2 becomes toxic to get3Δ but not to get5Δ cells. Together, these findings indicate an additional, Get5-independent role of Sgt2 in TA protein sorting, pointing to parallel pathways of substrate delivery to Get3.

Keywords: chaperone; GET pathway; Hsp70; protein quality control; protein targeting; TPR protein

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